1. Field of the Invention
The present invention relates to integrated circuit devices, and more specifically to an integrated circuit sample package for checking electrical functionality and alignment of checking devices that check mechanical and electrical features of integrated circuit devices.
2. Description of Related Art
According to technologies connected with the manufacture of integrated electronic circuit devices, package technology (i.e., the housing, usually of plastic material, that contains the silicon chip and is fitted with terminals or pins for connecting the integrated circuit to other circuits or printed circuit boards) plays an important role. Assembly of the chip into the package is a highly automated process that includes a step for checking both the electrical continuity between the various terminals and their correct alignment. A faulty alignment can cause a missing connection when assembling and testing the integrated circuit.
Such a checking step is typically executed by handler robots that pick up single packages containing the integrated chips through special chutes or pick-and-place systems and convey them onto a contactor (i.e., a contact array) whose configuration and array correspond to the terminals to be checked. The check executed at this stage (i.e., when the package is on the contactor) can vary from checking electrical continuity only to input-output functional checks of the integrated circuit. Therefore, contactor alignment and good operation is of primary importance in allowing a reliable reproducible checking of the features of the integrated circuit device to be performed.
A simple method for checking both the alignment and good operation of the handler's contactor is to use real packages containing chips. However, this has several drawbacks. First, it uses a finished product and consequently wastes it due to wear following a certain number of tests. Additionally, even if classed in the same package category, there may be different products apart from the electronic function of the integrated circuit. In particular, the material used to manufacture the terminals can differ from one product to another, so resilience of the terminals under the contactor pressure can vary or the pitch between the terminals can be different. As a result, a different sample has to be used for each product.
Moreover, repeated tests cause fast sample wear and alter the mechanical dimensions so as to make the checking results no longer reproducible. More specifically, the mechanical dimension of primary interest is a coplanarity of the contactor contacts with respect to the terminals. This ensures that no circuits will be open-circuit during the checking operation due to bad contactor coplanarity. Additionally, the horizontal contact alignment in line with the terminals is important to avoid one or more contacts coming in line with spaces between the terminals and giving an open circuit signal.
Such horizontal alignment is particularly important when the contactor uses "Kelvin" type contacts (i.e., contacts with a second "sense" terminal to compensate for ohmic resistance losses due to direct current application). In such cases, one or more terminals will probably not be correctly aligned and will then cause false checking results, or even damage the test circuits. Besides coplanarity, a particularly significant mechanical dimension that should be maintained constant during checking is the "stand-off" (i.e., the distance between the contactor plane and the lower side of the package). If this distance changes (and in particular decreases), then some difficulties are caused during insertion of a sample into the contactor.
One conventional solution for addressing such drawbacks is to use an empty package (i.e., one without a chip inside) whose terminals are electrically short-circuited. However, this does not obviate all of the above mentioned drawbacks, and in particular the drawbacks related to mechanical wear. Further, it does not provide for the manufacture of package samples with mechanical dimensions with different tolerances (e.g., minimum and maximum limits) to allow calibration of contactor accuracy because production packages are used (i.e., having a predetermined tolerance and not necessarily predetermined dimensions).